Fluid pressure tool



-Feb. 2l, 1933. G, M. NELL FLUID PRESSURE TOOL Filed Feb. l, 1929 2Sheets-Sheet `l 12km/Lm ATTORNEY,

Feb. 2l, 1933. G. M. NELL FLUID PRESSURE TOOL Filed Feb. l, 1929 2Sheets-Sheet 2 INVENTOR. Gasm/e /M A/@// 24 ,C www A TTORNE Y.

Patented Feb. 21, 1933 UNITED `STATES PATENT OFFICE GUSTAVE MLNELIJ, OFDETROIT', MICHIGAN, ASSIGNOR T0 CHICAGO PNEUMATIC TOOL COMPANY, NEWYORK, N. Y., A CORPORATION OF NEW JERSEY FLUID PRESSURE TooL Applicationfiled February 1, 1929. Serial No. 336,880.

This invention relates to fluid pressure motors of the type embodied inpercussive machines generally, of which pneumatic hammers and hammerdrills are the more common examples. More particularly it relates totools and machines using motors in which the distribution of the motivefiuid is controlled by a valve thrown automatically in timed relationwith the movements of the piston.

One object of the invention is to provide an improved form of percussivemotor having a simple, compact and easily assembled valve structure.Another object is to dispose the valve structure concentric with themain operating parts of the machine thereby to avoid the customary largeprojection which makes such machines awkward to handle and to operate.Another object is to provide for exact determination of the quantity ofmotive fluid passing to the ends of the piston chamber. Still anotherobject is to effect accuratelyitimed and positive movement of the valve.Other objects will be apparent from the detailed description whichfollows.

In order to illustrate the invention one concrete embodiment thereof andcertain modified forms of the valve are shown in the accompanyingdrawings in which:

Fig. 1 is a longitudinal sectional view of a percussive drill; Y

Fig. 2 is a sectional view of a detail of Fig. 1, namely the valveassemblyV and indicating a slight modification of the valve, the sectionbeing taken substantially on the line 2-2 of Figs. 3 and 4; l Y Figs. 3and 4 are respectively left and right end elevational or plan views ofthe ,valve assembly shown in Fig. 2

Fig. 5 is a sectional view substantially on the line 5--5 of Fig. 2showing'a modification of the valve; and

Fig. 6 is asectional view similar to Fig. 5 showing the valve of Fig. 1.Y f

In the embodiment of the invention chosen for the purpose ofillustration the cylinder 7 of the percussive drill has an atmosphericexhaust'port 8 intermediate its length arranged to be overrun andcontrolled by the hammer piston 9 which is reciprocated within thepiston chamber of the cylinder to impart blows to a suitable workingtool such as a drill steel 10. The steel is supported for rotation inthe chuck 11 in front head 12 and may be hollow to permit cleansingfluid to be fed thereto through the usual tube 13 extending axiallythrough the drill.

The rearward end of cylinder 7 is counterbored to receive and tosupport, in line with the piston chamber, a valve assembly whichpreferably comprises valve case 14, valve lid 15, and valve 36. In theform shown, a ratchet ring 17 is also inserted within the counterbore ofcylinder 7 against the valve chest to support the head of a rifle bar18,the bar portion of which extends through aligned bores v15a and 14aof parts 15 and 14 comprising the valve chest. A back head 19, in whichtube' 13 is preferably supported, engages ring 17 to hold the same andthe valve assembly in place in the cylinder, .the back headbeing in turnheld in place by any suitable means such as the usual side rods orthrough bolts (not shown).

As indicated, case 14 and lid 15, comprising the valve chest, providetherewithin valve chamber which in the present instance is annular inshape. An annular series of ports 2O open through one kend wall of thevalve chamber, namely, through case 14 (Figs. 1, 2, and 4) into the rearend of the piston chamber. A complementary series of ports 21 intheopposite end wall of the valve chamber, namely lid 15 open into passages21a which extend radially and then make a right-angular turn in aforward direction and register with connecting passages 21?) in case 14,and 210 in cylinder 7, to enter the piston chamber at the forward endthereof. Ports 2O land 21 are controlled by a suitable valve such as 36,which has end faces 36a and 365 for this purpose, and providetherebetween, within the valve itself, a chamber for pressure huid. Thevalve is shown as annular in shape and mounted for movement entirelywithin the confines of case 14. The valve may have a bearing or slidingfit with case 14 either on the inner or. outer peripheral wall of thevalve chamber. In Fig. 2, valve 16 slidingly engages only the centralboss of case 14, which boss is made hollov7 or perforate by reason ofthe bore 14a. The valves 26 of Fig. 5 and 36 of Figs. 1 and (S, have asliding fit or bearing upon both the inner and outer peripheral walls ofthe valve case 14.

Pressure fiuidis suppliedgto the central chamber of valves 16, 26, or 36frominlet 22 in the back head 19 which communicates with an annularchamber 22a inthe face of the headV adjacent vring 1,7. j An rannularseries of passages 22?) extend through ring 17 and register with similarpassages 220 ofcase 14, the latter passages taking av right-angular bendto open into the valve chamber substan-l tially centrally thereof. Themotive fluid in the central chamber of the valve isdistributedalterna-tely to ports 20 .and 21-at the ends of the valvechamber. depending upon the position of the valve. Means are provided,however, forirestricting the volume of motive fluid :to an amount lessthan the capacity of the ports at each end ofthe valve chamber. In theformfof the valve shown in Fig. 2, this is accomplished by extending theendfaces almost to the outer wall of the valve chamber but leaving 'anarrow peripheral passage, the extent of which is indicated Aby thespace between the two adjacent broken lines shown in Fig. 3. In Fig. 5the same result is accomplished with valve 26 bythe provision of aseries ofnotches 26a in the periphery thereof. Still'another variationis shown in Fig. 6 wherein the passage of motive fiuid through the end,faces of valve 36is provided for by ay series of ports 36a adjacent theouter edge ofthe same,

The. operation of the tool shown in Fig. 1 is briefly as follows: liththe parts in the position shown, motive fiuid is passing from thecentral l chamber of the valve through ports 36a in face 162) to portsY2,1 and thence by passages 21a, 2lb, and v210 to the forward end of thepiston chamber to drive piston 9 rearwardly, `the rear end of thepistonv cham-V ber being open to exhaust through port 8, and-`ports 20'of thel valve chest being sealed by'face 16a of the valve. As thepiston'inoves rearwardly, it closes exhaust 8 trapping a quantityof lairin thet piston chamber and compressing the same. Theair thuscompressed-acts through ports 20 against face 36a, ofmthe valve, vThenthe piston 9 lhas moved far enouglrto uncover port 8 and open theforward end of the piston chamber to atmosphere, there is a suddendropin pressure in passages 210, 2lb, 210i and port-s 21 with the result.that the valve moves 4quickly to its rearward position closingI ports21. The motive fluid from the central valve chamber new passes throughzface 36a to ports 2O driving the pist-on forwardly. As central exhaust 8is closed .by piston 9, pressure begins to build up in passages21c, 2lb,and 21a and this pressure 'becomes effective to shiftfthe valve back toits original position when piston 9 uncovers exhaust 8, as shown in Fig.1.

rlhe restriction in the movement of motive Huid from the central valvechamber to the end ports, aceo-mplished in any one of the ways indicatedin Figs. 2, 5, and .6, is of importance inthe shiftingmovement of thevalve since it prevents the passing of motive fluid in sufficientquantity to the exhaust side of the valve to interfere with the movementof the same. The effective pressure for throwing .the valve is increasedby enlarging ports 2O and 21 where they open into the valve chamber byflaring or counter-sinking the same as indicated at 20x and 21m, Figs. 1and 2.y lf desired, the throwing pressuremay also be increased byproviding one or more restricted. ports through each of the end facesofthe valve as indicated at 160 in Fig. 2. Similar ports for the samepurpose maybe provided in the modifications of the invention asindicated at 260 and 860 in Figs. 5 and 6 respectively. Alternatively oradditionally the outer end faces of the valves may be reduced or cutaway toward their periphery, indicatedat 16d (Fig. 2), to .provideannular relief areas supplied from the central chamber ofthe valve. Thisarrangement minimizes the intensity of the pressure necessary to startthe valve od its seat.

To maintain the control parts of the drill so that the communicatingpassages willialways be in register, long dowel pins 23 are providedwhich extend through suitable bores therefor in ring 17, lid 15, andease14 and have their ends received in suitable sockets in cylinder and backhead 19 respectively.

While the invention. has Ybeen herein disclosed in what is nowconsidered to be a preferred form with modifications, it is to beunderstood that the invention is not limited to the specific detailsthereof but covers all changes, modifications, and adaptations withinthe scope ofthe appended claims.

I vclaim as my invention:

1. In a. fluid pressure motor, a cylinder having an exhaust portintermediatel its length a piston reciproeable in said cylinder andcontrolling'said port, a valve chest in line with the piston Achamberand serving as a closure for the latter, said chest vproviding anannular valve chamber and having ports at the ends thereof Vleading toopposite ends ofthe piston chamber,an annular'valve having end faces forcontrolling the ports in said valve chest and an intermediate reser-vVoir for pressure fluid, and lmeans comprising ports in the end faces ofsaid rvalve restricting the movement of pressure fluid'from saidreservoir to each groupfof end portsin said valve chamber to an'amountless than the capacity of each group.

2.. In a fluid pressure motor, a cylinder having anexhaust portintermediate y its length, a piston reciprocable in said cylinder leoand controlling said port, a valve chest in line with the piston chamberand serving as a closure for the latter, said chest providing an annularvalve chamber and having ports at the ends thereof leading to oppositeends of the piston chamber, an annular valve having end faces forcontrolling the ports in said valve chest and an intermediate reservoirfor pressure iuid, and means comprising ports in the end faces of saidvalve restricting the movement of pressure fluid from said reservoir toeach group of end ports in said valve chamber to an amount less than thecapacity of each group, said valve ports being out of register with saidchest ports in all positions of said valve.

3. In a fluid pressure motor, a cylinder having an exhaust portintermediate its length, a piston reciprocable in said cylinder andcontrolling said port, a valve chest in line With the piston chamber andserving as a closure for said cylinder, said chest providing an annularvalve chamber and ports at the opposite ends thereof leading to oppositeends of the piston chamber, an annular valve providing end faces forcontrolling the ports in said valve chest, and an intermediate reservoirfor pressure fluid, said valve having ports out of register With saidchest ports but arranged to permit the passing of pressure fluid fromsaid reservoir alternately to eaoh end group of chest ports in lessvolume than the capacity of each end group, said valve being moved byair compressed by the piston at the end of each stroke and having atleast one restricted port through each end face to permit a limitedamount of pressure fluid from said reservoir to reach the closed portsand augment the air compressed by the piston.

fl. In a fluid pressure motor having a cylinder and a pistonreeiprocable therein, a valve chest providing an annular valve chamberand ports at the opposite ends thereof leading to opposite ends of thepiston chamber, and an annular valve having end faces for controllingsaid ports and providing an intermediate reservoir for pressure fluid,said valve slidably engaging both the inner and outer Walls of saidchest and having means for passing pressure luid from said reservoir tosaid ports in alternation, said last mentioned means being of lowercapacity than said-ports.

Signed by me at Detroit, in the county of Wayne, and State of Michigan,this 28th day of January, 1929.

GUSTAVE M. NELL.

